Egypt’s President Mohamed Morsi is facing international pressure to engage in “serious national dialogue” hours after he rebuffed an army ultimatum to find a solution to the political crisis.

The UN human rights office called on Morsi’s government on Tuesday to listen to the demands of the Egyptian people and engage in a “serious national dialogue” to defuse the crisis.

Rupert Colville, the spokesman of the UN High Commissioner for Human Rights, Navi Pillay, also said the role of the Egyptian military was crucial.

“Nothing should be done that would undermine democratic processes,” he said.

Earlier, the US President, Barack Obama, spoke to the Egyptian leader via phone. A White House statement said he “stressed that democracy is about more than elections; it is also about ensuring that the voices of all Egyptians are heard and represented by their government, including the many Egyptians demonstrating throughout the country”.

The army on Monday said it would intervene if a solution to the crisis was not found within 48 hours. Tahrir Square in Cairo was full for the third day of anti-Morsi protests on Tuesday, while supporters of the president held their own rally in Nasr City.

In a statement issued nine hours after that deadline was imposed, the president’s office said: “The president of the republic was not consulted about the statement issued by the armed forces.

“The presidency sees that some of the statements in it carry meanings that could cause confusion in the complex national environment.”

Morsi met the head of the armed forces, General Abdel Fattah al-Sisi, for a second day, the president’s office said later on Tuesday.

The protests have drawn at least 14 million people onto the streets, with a large number of them demanding Morsi’s resignation.

Spate of resignations

The crisis has triggered a series of resignations by cabinet ministers, leaving Morsi isolated.

Senior officials who have quit include foreign minister Mohamed Kamel Amr, who tendered his resignation on Tuesday.

Others to resign are tourism minister Hisham Zaazou; communication and IT minister Atef Helmi; the minister for legal and parliamentary affairs, Hatem Bagato; water minister Abdel Qawy Khalifa; and environment minister Khaled Abdel-Aal.

Morsi also lost the support of Sami Enan, his military adviser, who resigned and said the army would not “abandon the will of the people”.

Opponents of Morsi viewed the army statement as an endorsement and continued to flood the streets to press on the president to step down.

Morsi supporters criticised the ultimatum as an attempted coup. A group of pro-Morsi parties, calling themselves the “coalition to defend legitimacy,” called for mass protests in support of the president during a late-night press conference.

“We reject attempts to use the army to attack the legitimacy of the president,” said Safwat Abdel Ghani, a senior member of the Gamaa al-Islamiyya.

Tamarod, the grassroots campaign behind the latest anti-Morsi protests, praised the statement, saying it showed the military was on the side of the people. Its own deadline for Morsi to resign – 15.00GMT on Tuesday – looks set to pass.

The June 30 Front, an opposition umbrella group which includes Tamarod, on Tuesday said it had chosen Mohamed ElBaradei to represent it at any politicial transition.

* Published under an agreement with Al Jazeera